Currently, the conventional compressing diaphragm pumps exclusively used with RO (Reverse Osmosis) purifier or RO water purification system, which is popularly installed on the water supplying apparatus in either the settled home, recreational vehicle or mobile home, have some various types. For four-booster-chamber diaphragm pumps, other than the specific type as disclosed in the U.S. Pat. No. 6,840,745, the majority of conventional four-booster-chamber diaphragm pumps can be categorized as similar design as shown in FIGS. 1 through 10. An essential configuration of the conventional four-booster-chamber diaphragm pumps aforesaid can be generalized as similar design as shown in FIGS. 1 through 10, which essentially comprises a motor 10 with an output shaft 11, a motor upper chassis 30, a wobble plate with integral protruding cam-lobed shaft 40, an eccentric roundel mount 50, a pump head body 60, a diaphragm membrane 70, four pumping pistons 80, a piston valvular assembly 90 and a pump head cover 20, wherein said motor upper chassis 30 includes a bearing 31 to be run through by the output shaft 11 of the motor 10, an upper annular rib ring 32 with several internal and external fastening bores 33 evenly disposed inner and outer of circumferential rim thereof; said wobble plate with integral protruding cam-lobed shaft 40 includes a shaft coupling hole 41 for being run through by the corresponding motor output shaft 11 of the motor 10; said eccentric roundel mount 50 includes a central bearing 51 securely fitted at the bottom base thereof for engaging with the corresponding wobble plate with integral protruding cam-lobed shaft 40, four truncated-cylinder eccentric roundels 52 disposed on the bottom base thereof in circumferential location evenly such that each truncated-cylinder eccentric roundel 52 has a horizontal top face 53, a truncated cylinder peripheral 56, a female-threaded bore 54 and an annular positioning dent 55 formed on the top face thereof respectively in horizontal flush, as well as a rounded shoulder 57 created at the joint of the horizontal top face 53 and truncated cylinder peripheral 56; said pump head body 60, which suitably covers on the upper annular rib ring 32 of the motor upper chassis 30 to encompass the wobble plate with integral protruding cam-lobed shaft 40 and eccentric roundel mount 50 therein, includes four operating holes 61 disposed therein in circumferential location evenly such that each operating hole 61 has inner diameter slightly bigger than outer diameter of the corresponding truncated-cylinder eccentric roundel 52 in the eccentric roundel mount 50 for receiving each corresponding truncated-cylinder eccentric roundel 52 respectively, a lower annular flange 62 formed thereunder for mating with corresponding upper annular rib ring 32 of the motor upper chassis 30, several internal and external fastening bores 63 evenly disposed inner and outer of circumferential thereof; said diaphragm membrane 70, which is extrude-molded by semi-rigid elastic material and to be placed on the pump head body 60, includes a pair of parallel outer raised brim 71 and inner raised brim 72 as well as four evenly spaced radial raised partition ribs 73 such that each inner end of radial raised partition rib 73 connects with the inner raised brim 72 so that four equivalent piston acting zones 74 are formed and partitioned by the radial raised partition ribs 73, wherein each piston acting zone 74 has an acting zone hole 75 created therein in correspondence with each female-threaded bore 54 in the truncated-cylinder eccentric roundel 52 of the eccentric roundel mount 50 respectively, and an annular positioning protrusion 76 for each acting zone hole 75 is formed at the bottom side of the diaphragm membrane 70 (as shown in FIGS. 8 and 9); each said pumping piston 80, which is respectively placed in each corresponding piston acting zones 74 of the diaphragm membrane 70, has a tiered hole 81 run through thereof so that each said pumping piston 80 is respectively disposed in each corresponding piston acting zones 74 of the diaphragm membrane 70 after having each annular positioning protrusion 76 in the diaphragm membrane 70 inserted into each corresponding annular positioning dent 55 in the truncated-cylinder eccentric roundel 52 of the eccentric roundel mount 50 by running fastening screw 1 through the tiered hole 81 of each pumping piston 80 and the acting zone hole 74 of each corresponding piston acting zone 74 in the diaphragm membrane 70 with result that the diaphragm membrane 70 and four pumping pistons 80 can be securely screwed into each female-threaded bore 54 of corresponding four truncated-cylinder eccentric roundels 52 in the eccentric roundel mount 50 (as enlarged view shown in FIG. 10 of association); said piston valvular assembly 90 includes a downward outlet raised brim 91 to insert an indented brim formed between the outer raised brim 71 and inner raised brim 72 in the diaphragm membrane 70, a central dish-shaped round outlet mount 92 having a central positioning bore 93 with four equivalent sectors such that each sector contains a group of multiple evenly circum-located outlet ports 95, a T-shaped plastic anti-backflow valve 94 with a central positioning shank, and four circumjacent inlet mounts 96 such that each inlet mount 96 includes a group of multiple evenly circum-located inlet ports 97 and an inverted central piston disk 98 respectively so that each piston disk 98 serves as a valve for each corresponding group of multiple inlet ports 97, wherein the central positioning shank of the plastic anti-backflow valve 94 mates with the central positioning bore 93 of the central outlet mount 92 such that each group of multiple outlet ports 95 in each sector of the central round outlet mount 92 is communicable with each corresponding group of inlet ports 97 in each corresponding inlet mount 96, and a hermetical pressure booster chamber 26 is formed between each inlet mount 96 and corresponding piston acting zone 74 in the diaphragm membrane 70 upon the downward outlet raised brim 91 having inserted the indented brim formed between the outer raised brim 71 and inner raised brim 72 in the diaphragm membrane 70 (as enlarged view shown in FIG. 10 of association); and said pump head cover 20, which directly covers on the pump head body 60 to encompass the piston valvular assembly 90, four pumping pistons 80 and diaphragm membrane 70 therein, includes a water inlet orifice 21, a water outlet orifice 22, and several internal and external fastening bores 23 while a tiered rim 24 and an annular rib ring 25 are disposed in the bottom inside thereof so that the outer brim of the pump head cover 20 after assembling of diaphragm membrane 70 and piston valvular assembly 90 can hermetically attach on the tiered rim 24 (as enlarged view shown in FIG. 10 of association), wherein a compressing chamber 27 is configured between cavity formed by the inside wall of the annular rib ring 25 and the central outlet mount 91 of the piston valvular assembly 90 upon having the bottom of the annular rib ring 25 closely covered on the brim of the central outlet mount 92 (as shown in FIG. 10).
By running each internal and external fastening bolt 2 through the each corresponding internal and external fastening bores 23 of pump head cover 20 and each corresponding internal and external fastening bore 63 in the pump head body 60 as well as each corresponding internal fastening bore 33 in the motor upper chassis 30, then putting a nut 3 onto each external fastening bolt 2 to securely screw each corresponding external fastening bore 33 in the pump head cover 20 and pump head body 60 so that the assembly of the four-booster-chamber diaphragm pump is finished (as shown in FIGS. 1 and 10).
Please refer to FIGS. 11 and 12, which are illustrative figures for the operation of conventional four-booster-chamber diaphragm pump aforesaid. When the motor 10 is powered on, the wobble plate 40 is driven to rotate by the motor output shaft 11 so that four truncated-cylinder eccentric roundels 52 on the eccentric roundel mount 50 orderly move in up-and-down reciprocal stroke constantly; Meanwhile, four pumping pistons 80 and four piston acting zones 74 in the diaphragm membrane 70 are orderly driven by the up-and-down reciprocal stroke of four truncated-cylinder eccentric roundels 52 to move in up-and-down displacement; As the truncated-cylinder eccentric roundel 52 moves in “down stroke” with pumping piston 80 and piston acting zone 74 in down displacement, the piston disk 98 in the piston valvular assembly 90 is pushed into “open” status so that the tap water W can flow into the pressure booster chamber 26 orderly via water inlet orifice 21 in the pump head cover 20 and inlet ports 97 in the piston valvular assembly 90 (as shown in FIG. 11 and arrowhead indication W in enlarged view of association) while the truncated-cylinder eccentric roundel 52 moves in “up stroke” with pumping piston 80 and piston acting zone 74 in up displacement, the piston disk 96 in the piston valvular assembly 90 is pulled into “close” status to compress the tap water W in the pressure booster chamber 26 to increase the water pressure therein up to range of 100-150 psi and become into pressurized water Wp with result that the plastic anti-backflow valve 94 in the piston valvular assembly 90 is pushed to “open” status; Since the plastic anti-backflow valve 94 in the piston valvular assembly 90 is pushed to “open” status, the pressurized water Wp in the pressure booster chamber 26 is directed into compressing chamber 27 via group of outlet ports 95 for the corresponding sector in central outlet mount 92, then expelled out of the water outlet orifice 22 in the pump head cover 20 (as shown in FIG. 12 and arrowhead indication Wp in enlarged view of association); consequently, with orderly repeat action for each group of outlet ports 95 for four sectors in central outlet mount 92, the pressurized water Wp is constantly discharged out of the conventional four-booster-chamber diaphragm pump for being further RO-filtered by the RO-cartridge so that the final filtered pressurized water Wp can be used in the RO (Reverse Osmosis) purifier, which is popularly installed on the water supplying apparatus in the settled home, and RO water purification system in the recreational vehicle or mobile home.
Referring to FIGS. 13 and 14, some drawbacks have long-lasting existed in the foregoing conventional four-booster-chamber diaphragm pump as below. As described previously, when the motor 10 is powered on, the wobble plate 40 is driven to rotate by the motor output shaft 11 so that four truncated-cylinder eccentric roundels 52 on the eccentric roundel mount 50 orderly move in up-and-down reciprocal stroke constantly, and four piston acting zones 74 in the diaphragm membrane 70 are orderly driven by the up-and-down reciprocal stroke of four truncated-cylinder eccentric roundels 52 to move in up-and-down displacement so that equivalently a repeated acting force F constantly acting on the bottom side of each said piston acting zone 74. Meanwhile a plurality of rebounding force Fs is created to react the acting force F exerting on the bottom side of diaphragm membrane 70 with different components distributed over entire bottom area of each corresponding piston acting zone 74 in the diaphragm membrane 70 (as distributed component forces shown in FIG. 14) so that a “squeezing phenomenon” happens on the partial portion of the diaphragm membrane 70, which is incurred by the rebounding force Fs. Among all distributed component forces of the rebounding force Fs, the specific component force happened at the contacting bottom position P of the diaphragm membrane 70 with the rounded shoulder 57 of the horizontal top face 53 in the truncated-cylinder eccentric roundel 52 is maximum so that the “squeezing phenomenon” happened here is also maximum (as shown in FIG. 14). With rotational speed for the motor output shaft 11 of the motor 10 reaching a range of 800-1200 rpm, each bottom position P at the piston acting zone 74 of the diaphragm membrane 70 is suffered from the “squeezing phenomenon” in a frequency of four times per second. Under such circumstance, the bottom position P of the diaphragm membrane 70 is always the first broken place for entire conventional four-booster-chamber diaphragm pump, which is the essential cause for not only shortening the service lifespan but also terminating normal function of the conventional four-booster-chamber diaphragm pump.
Therefore, how to substantially reduce all the drawbacks associated with the “squeezing phenomenon” caused by the repeated acting force F constantly acting on the bottom side of each said piston acting zone 74 of the diaphragm membrane 70, which is incurred by the truncated-cylinder eccentric roundel 52, for the conventional four-booster-chamber diaphragm pump becomes an urgent and critical issue.